Background: The Lymphohematopoietic Cancer (LHC) incidence rate in Thailand has been rising over the past decade with unknown etiology, including Rayong province. One hypothesis of LHC risks is exposure to occupational carcinogens.
Objective: To determine the association of occupational exposure and LHC risks in Rayong province, Thailand.
Material and Method: This matched hospital-based case-control study was conducted in a Rayong provincial hospital from September 2009 to January 2013. One LHC case was matched with four controls in gender and age, +5 years. Demographic data, residential factors, behavioral factors, and occupational exposure-including chemical exposure-were obtained by interviews and collected by occupational health care officers. The risk factor was analyzed by conditional logistic regression and reported in odds ratio with 95% confidence interval.
Results: This study found 105 LHC cases which met the inclusion criteria and were included in the study, yielding a 66% cover rate of cases reported in the database. The histology of LHC were 51 leukemia cases (47.7%), 43 lymphoma cases (42.0%), and 11 multiple myeloma cases (10.3%). The results revealed that occupational exposure to pesticide and smoke were statistically significantly associated with LHC with adjusted ORs 2.26 (95% CI 1.30-3.91) and 1.99 (95% CI = 1.13-3.51),
respectively. When stratified to histological subtype of LHC by WHO 2000, leukemia was statistically significantly associated
with occupational exposure to smoke, adjusted ORs 2.43 (95% CI 1.11-5.36), with occupational pesticide exposure a significant risk of lymphoma, adjusted ORs 4.69 (95% CI 2.01-10.96). However, neither fumes, wood dust, working
outdoors, cleaners, contact with animals, petroleum products and chlorine; nor occupational exposure to volatile organic
compounds (VOCs) such as benzene or organic solvents, were statistically significant risk factors of LHC. In addition, there
were no significant risks in the demographic data, residential factors, and behavioral factors.
Conclusion: Occupational exposure to pesticides and smoke were important occupational risks in developing LHC in Rayong province. However, the ability or power to detect this problem due to the small sample size and recall bias from the study design could not be excluded.

Keywords: Lymphohematopoietic cancer, Occupational risk factor, Occupational exposure